1. Field of the Invention
The invention relates to a vehicle seat provided with a frame member, an engaging portion that is able to engage with a vehicle cabin structure, and a retaining portion that is able to retain a band member.
2. Description of Related Art
One such vehicle seat that is well known is provided with a seat cushion and a seat back (see Japanese Patent Application Publication No. 2001-314272 (JP 2001-314272 A). The seat back is connected in a raisable manner to the seat cushion. The seat back has a frame member, an engaging portion, and a retaining portion. The frame member is a generally rectangular frame-shaped member, and includes an upper pipe that forms an upper portion when upright, a lower pipe that forms a lower portion, and connecting pipes. The frame member is made of highly rigid metal. The connecting pipes connect the upper pipe to the lower pipe, and may be arranged in the center and on both sides of the seat back. Also, the engaging portion is a portion formed recessed in the thickness direction of the seat, and may be arranged on one side of the upper portion of the frame member when the seat back is upright. In the related art, a rod member is provided on the vehicle cabin structure and extends in the seat width direction. The seat back is able to be supported by the vehicle cabin structure by fitting the rod member into the engaging portion while the seat back is raised.
An object such as a child seat may be attached to a sitting side of the vehicle seat. A strap member (a band member) is attached to an upper portion of the child seat, and may be attached to a retaining portion on a back surface of the seat back. In the related art, after the child seat is arranged on the sitting side of the seat, the strap member is extended from a shoulder (i.e., the other side of the upper portion of the frame member) of the seat back to the rear surface of the seat back, and fixed to the retaining portion. The other side of the upper portion of the frame member is the side of the upper portion of the frame member on which the engaging portion is not provided.
Here, with the seat structure described above, stress may be applied to the frame member when the strap member is strained or the like when the vehicle is involved in a collision. That is, when tension is placed on the strap member, stress (i.e., bending stress) is consequently applied to the frame member of the upright seat back on a virtual diagonal line that connects the one side of the upper portion of the seat back with the other side of the lower portion of the seat back. At this time, with the related art, the frame member is prevented to the greatest extend possible from bending by the stress described above because the entire frame member is made of highly rigid metal.